Field of the Invention
The invention relates in general to Viterbi decoding technologies, and more particularly to a Viterbi decoding technology capable of providing two types of decoded results.
Description of the Related Art
Concatenated error correction codes currently applied to numerous types of communication systems and signal broadcasting systems enhance the performance of encoded results through combining two or more encoding technologies. A receiver in such system needs to first perform an inner code decoding process, and then perform an outer code decoding process on the inner code decoded result. Taking a Digital Video Broadcasting—Terrestrial (DVB-T) system for example, the receiver needs to decode convolutional encoded data by a Viterbi decoder and then sends the decoded result to a Reed-Solomon decoder. Generally known to one person skilled in the art, a typical Viterbi decoder selects an optimum decoded result from many possible decoded results and provides the selected optimum decoded result to the Reed-Solomon decoder. However, the optimum decoded result identified by the Viterbi decoder may not be correct data (i.e., actual data transmitted by the transmitter). In the above situation, the Reed-Solomon decoder is usually incapable of decoding such packet as the packet contains too many errors. To solve the above issue, in a current approach, the Viterbi decoder is designed to provide more than one decoded result (e.g., simultaneously providing an optimum decoded result and a second optimum decoded result) to the Reed-Solomon decoder. If the Reed-Solomon decoder cannot decode the optimum packet, it may attempt to decode the second optimum decoded result, hence enhancing the probability of successful decoding.